Abstract
The abilities of 44 bacterial epiphytes to reduce leaf-associated population sizes of Xanthomonas translucens pv. translucens strain Xtt4Rif-2 and bacterial leaf streak were quantified in growth-chamber experiments. Bacterial epiphytes were inoculated individually onto 10-day-old wheat seedlings at a density of 108 CFU/ml. Pathogen strain Xtt4Rif-2 was inoculated onto wheat seedlings 48 h later at a density of 107 CFU/ml. Population sizes of the bacterial epiphytes and the pathogen were quantified 48 h after inoculation of the pathogen and disease severity was assessed 5-6 days later. Thirteen bacterial epiphytes were identified by their ability to reduce Xtt4Rif-2 populations, disease severity, or both compared to a pathogen-only control (subsequently referred to as successful antagonists). The potential roles of antibiosis and competition for nutrient resources in mediating the observed interactions between the epiphytes and the pathogen were also investigated. Only one epiphyte inhibited Xtt in vitro. Thus, antibiosis probably was not a major mechanism by which pathogen population sizes and disease severity were reduced. Similarity in nutrient utilization between bacterial epiphytes and pathogen strain Xtt4Rif-2 was estimated using nutrient-overlap indices. Nutrient-overlap indices were not predictive of the ability of epiphytes to reduce pathogen populations or disease severity. However, successful antagonists utilized both sucrose and inositol more frequently than poor antagonists. (C) Academic Press.
Original language | English (US) |
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Pages (from-to) | 61-72 |
Number of pages | 12 |
Journal | Biological Control |
Volume | 17 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2000 |
Bibliographical note
Funding Information:We thank the Department of Plant Pathology at the University of Minnesota and the USDA, ARS Cereal Disease Laboratory for their support of this work. The research was conducted under Project 22-18H, USDA NRI Competitive Grant 9702714 to Linda Kinkel and Kurt Leonard and a grant from the University of Minnesota College of Agriculture, Food, and Environment Biological Control Reallocation Fund to Kurt Stromberg. We thank Andrew Ryan, Kyoko Shimizu, and Miriam Newton for their excellent technical support and R. J. Jones, E. A. Milus, and R. L. Forster for kindly donating bacterial isolates. Mention of a trademark name or proprietary product does not constitute a guarantee or warranty by the U. S. Department of Agriculture or the University of Minnesota nor imply its approval to the exclusion of other products that may also be suitable.